Free-space Beam Steering Systems, Devices, and Methods

ABSTRACT

Devices and systems having a vertical waveguide array are provided having a plurality of vertical waveguides disposed on a support substrate in an array, where each vertical waveguide further includes a reflective region positioned to reflect impinging light toward the support substrate, a core region extending from the reflective region to the support substrate, the core region further comprising, a first contact region and a second contact region electrically isolated from one another disposed between the reflective region and the support substrate, and a light concentrator disposed between the first contact region and the second contact region. The first contact region and the second contact region are operable to create a voltage drop across the light concentrator and the light concentrator has a lower refractive index compared to the refractive indexes of the first contact region and the second contact region. Additionally, a confinement structure surrounds the periphery of each waveguide, where the confinement structure has a lower refractive index compared to the refractive indexes of the first contact region and the second contact region.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.17/009,774, filed on Sep. 1, 2020, which claims the benefit of U.S.Provisional Patent Application No. 62/869,559, filed on Jul. 1, 2019,which is incorporated herein by reference in its entirety.

BACKGROUND

Electromagnetic radiation often is in the form of beams. To make use ofsuch beams, they often must be directed, or steered, to where it isneeded for an application. For example, this might be done for cuttingand drilling, for exposing a target and measuring one or more of itsproperties, for free-space communications, or for Light Detection AndRanging (LIDAR). In some examples, such LIDAR systems can be used tomeasure the environment and provide information to other systems. Inother examples, this information can be displayed for current use,and/or stored for later use.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a flash LIDAR device in accordance with an exampleembodiment;

FIG. 2 illustrates a technique for sampling a scene laterally using ascanning LIDAR in accordance with an example embodiment;

FIG. 4 illustrates an example of a beam steering system in accordancewith an example embodiment;

FIG. 5 illustrates an example of a beam steering system in accordancewith an example embodiment;

FIG. 6 illustrates an example of a beam steering system in accordancewith an example embodiment;

FIG. 7 illustrates an example of a beam steering system in accordancewith an example embodiment;

FIG. 8 illustrates an example of a beam steering device in accordancewith an example embodiment;

FIG. 9 illustrates an example of a beam steering device in accordancewith an example embodiment;

FIG. 10 illustrates an example of a beam steering circuitry inaccordance with an example embodiment;

FIG. 11 illustrates an example of a beam steering device in accordancewith an example embodiment;

FIG. 12 illustrates an example of a beam steering device in accordancewith an example embodiment;

FIG. 13 illustrates an example of a beam steering device in accordancewith an example embodiment;

FIG. 14 illustrates an example of a beam steering device in accordancewith an example embodiment;

FIG. 15 illustrates an example of a beam steering device in accordancewith an example embodiment;

FIG. 16 illustrates an example of a beam steering device in accordancewith an example embodiment;

FIG. 17 illustrates an example of a beam steering device in accordancewith an example embodiment;

FIG. 18 illustrates an example of a beam steering device in accordancewith an example embodiment;

FIG. 19 illustrates an example of a beam steering device in accordancewith an example embodiment;

FIG. 20 illustrates an example of a beam steering device in accordancewith an example embodiment; and

FIG. 21 illustrates an example of a beam steering device in accordancewith an example embodiment;

DESCRIPTION OF EMBODIMENTS

Although the following detailed description contains many specifics forthe purpose of illustration, a person of ordinary skill in the art willappreciate that many variations and alterations to the following detailscan be made and are considered included herein. Accordingly, thefollowing embodiments are set forth without any loss of generality to,and without imposing limitations upon, any claims set forth. It is alsoto be understood that the terminology used herein is for describingparticular embodiments only, and is not intended to be limiting. Unlessdefined otherwise, all technical and scientific terms used herein havethe same meaning as commonly understood by one of ordinary skill in theart to which this disclosure belongs. Also, the same reference numeralsin appearing in different drawings represent the same element. Numbersprovided in flow charts and processes are provided for clarity inillustrating steps and operations and do not necessarily indicate aparticular order or sequence.

Furthermore, the described features, structures, or characteristics canbe combined in any suitable manner in one or more embodiments. In thefollowing description, numerous specific details are provided, such asexamples of layouts, distances, network examples, etc., to provide athorough understanding of various embodiments. One skilled in therelevant art will recognize, however, that such detailed embodiments donot limit the overall concepts articulated herein, but are merelyrepresentative thereof. One skilled in the relevant art will alsorecognize that the technology can be practiced without one or more ofthe specific details, or with other methods, components, layouts, etc.In other instances, well-known structures, materials, or operations maynot be shown or described in detail to avoid obscuring aspects of thedisclosure.

In this application, “comprises,” “comprising,” “containing” and“having” and the like can have the meaning ascribed to them in U.S.Patent law and can mean “includes,” “including,” and the like, and aregenerally interpreted to be open ended terms. The terms “consisting of”or “consists of” are closed terms, and include only the components,structures, steps, or the like specifically listed in conjunction withsuch terms, as well as that which is in accordance with U.S. Patent law.“Consisting essentially of” or “consists essentially of” have themeaning generally ascribed to them by U.S. Patent law. In particular,such terms are generally closed terms, with the exception of allowinginclusion of additional items, materials, components, steps, orelements, that do not materially affect the basic and novelcharacteristics or function of the item(s) used in connection therewith.For example, trace elements present in a composition, but not affectingthe compositions nature or characteristics would be permissible ifpresent under the “consisting essentially of” language, even though notexpressly recited in a list of items following such terminology. Whenusing an open-ended term in this written description, like “comprising”or “including,” it is understood that direct support should be affordedalso to “consisting essentially of” language as well as “consisting of”language as if stated explicitly and vice versa.

As used herein, the term “substantially” refers to the complete ornearly complete extent or degree of an action, characteristic, property,state, structure, item, or result. For example, an object that is“substantially” enclosed would mean that the object is either completelyenclosed or nearly completely enclosed. The exact allowable degree ofdeviation from absolute completeness may in some cases depend on thespecific context. However, generally speaking the nearness of completionwill be so as to have the same overall result as if absolute and totalcompletion were obtained. The use of “substantially” is equallyapplicable when used in a negative connotation to refer to the completeor near complete lack of an action, characteristic, property, state,structure, item, or result. For example, a composition that is“substantially free of” particles would either completely lackparticles, or so nearly completely lack particles that the effect wouldbe the same as if it completely lacked particles. In other words, acomposition that is “substantially free of” an ingredient or element maystill actually contain such item as long as there is no measurableeffect thereof.

As used herein, the term “about” is used to provide flexibility to agiven term, metric, value, range endpoint, or the like. The degree offlexibility for a particular variable can be readily determined by oneskilled in the art. However, unless otherwise expressed, the term“about” generally provides flexibility of less than 1%, and in somecases less than 0.01%. It is to be understood that, even when the term“about” is used in the present specification in connection with aspecific numerical value, support for the exact numerical value recitedapart from the “about” terminology is also provided.

As used herein, a plurality of items, structural elements, compositionalelements, and/or materials may be presented in a common list forconvenience. However, these lists should be construed as though eachmember of the list is individually identified as a separate and uniquemember. Thus, no individual member of such list should be construed as ade facto equivalent of any other member of the same list solely based ontheir presentation in a common group without indications to thecontrary.

Concentrations, amounts, and other numerical data may be expressed orpresented herein in a range format. It is to be understood that such arange format is used merely for convenience and brevity and thus shouldbe interpreted flexibly to include not only the numerical valuesexplicitly recited as the limits of the range, but also to include allthe individual numerical values or sub-ranges encompassed within thatrange as if each numerical value and sub-range is explicitly recited. Asan illustration, a numerical range of “about 1 to about 5” should beinterpreted to include not only the explicitly recited values of about 1to about 5, but also include individual values and sub-ranges within theindicated range. Thus, included in this numerical range are individualvalues such as 2, 3, and 4 and sub-ranges such as from 1-3, from 2-4,and from 3-5, etc., as well as 1, 1.5, 2, 2.3, 3, 3.8, 4, 4.6, 5, and5.1 individually.

This same principle applies to ranges reciting only one numerical valueas a minimum or a maximum. Furthermore, such an interpretation shouldapply regardless of the breadth of the range or the characteristicsbeing described.

Reference throughout this specification to “an example” means that aparticular feature, structure, or characteristic described in connectionwith the example is included in at least one embodiment. Thus,appearances of phrases including “an example” or “an embodiment” invarious places throughout this specification are not necessarily allreferring to the same example or embodiment.

The terms “first,” “second,” “third,” “fourth,” and the like in thedescription and in the claims, if any, are used for distinguishingbetween similar elements and not necessarily for describing a particularsequential or chronological order. It is to be understood that the termsso used are interchangeable under appropriate circumstances such thatthe embodiments described herein are, for example, capable of operationin sequences other than those illustrated or otherwise described herein.Similarly, if a method is described herein as comprising a series ofsteps, the order of such steps as presented herein is not necessarilythe only order in which such steps may be performed, and certain of thestated steps may possibly be omitted and/or certain other steps notdescribed herein may possibly be added to the method.

The terms “left,” “right,” “front,” “back,” “top,” “bottom,” “over,”“under,” and the like in the description and in the claims, if any, areused for descriptive purposes and not necessarily for describingpermanent relative positions. It is to be understood that the terms soused are interchangeable under appropriate circumstances such that theembodiments described herein are, for example, capable of operation inother orientations than those illustrated or otherwise described herein.

As used herein, comparative terms such as “increased,” “decreased,”“better,” “worse,” “higher,” “lower,” “enhanced,” and the like refer toa property of a device, component, or activity that is measurablydifferent from other devices, components, or activities in a surroundingor adjacent area, in a single device or in multiple comparable devices,in a group or class, in multiple groups or classes, or as compared tothe known state of the art. For example, a data region that has an“increased” risk of corruption can refer to a region of a memory devicewhich is more likely to have write errors to it than other regions inthe same memory device. A number of factors can cause such increasedrisk, including location, fabrication process, number of program pulsesapplied to the region, etc.

An initial overview of embodiments is provided below, and specificembodiments are then described in further detail. This initial summaryis intended to aid readers in understanding the disclosure more quickly,and is not intended to identify key or essential technological features,nor is it intended to limit the scope of the claimed subject matter.

LIDAR can be used for measuring and/or imaging scenes in threedimensions (3-D). The typical data set a LIDAR system can produce iscalled a point cloud and can include distance/range values as a functionof position within the LIDAR device field of view (FOV). Eachdetermination of the distance value may correspond to the measurement ofthe time-of-flight (TOF), that is, the time it takes for one or morephotons to travel from a source, to the scene, and then reflect back toa sensor.

As with typical two-dimensional (2-D) intensity imagers, conventionalLIDAR systems can sample the lateral space. One class of systems thatcan do this is the so-called flash LIDAR, shown in FIG. 1, which is mostanalogous to the typical photographic camera operation. Here a scene 103can be uniformly illuminated with a source 101 (in some examples, asingle source), and an array of detectors 106 can measure photon TOF forphotons 104 that reflect back to it, thereby acquiring range informationand the data sufficient to form a 3-D point cloud image. This processmay be repeated multiple times and combined to produce a final singleimage in order to improve performance and SNR. This process can haveadvantages, including but not limited to the potential for single-shotimaging, and a simple, single, unstructured illumination source. It alsocan have drawbacks, including the need for expensive detector arrays,higher illumination power requirements, and a limited ability toleverage techniques such as compressed sensing.

A scene can also be sampled laterally using a scanning LIDAR, shown inFIG. 2. Instead of illuminating the entire scene 203, one or moreillumination sources 201 can be directed as beams to a small region ofthe scene, and then scanned as indicated by arrows 207 over time throughthe lateral dimensions to cover the entire scene 203. As this happens,one or more detectors 206 can measure the photons' TOF. This data can becollected as the scene is scanned, at the end of which an image can begenerated. This can have advantages that the illumination source can besimple and unstructured, and it may not require expensive sensor arrays.

One straightforward approach to beam steering for scanning LIDAR is touse reflective galvanometers, spinning polygons/prisms, or other typesof actuated sub-systems. Other approaches to scanning include the use ofspatial light modulators (SLMs), which are generally composed of anarray of modulating elements, herein referred to as pixels. Such SLMscan include digital micromirror devices (DMDs), liquid crystal onsilicon (LCoS), and others. Yet another approach is photonic integratedcircuit (PIC)-based optical phased arrays (OPAs). The latter class ofsystems has no moving parts, and is often made in silicon and/or useselectromagnetic radiation with wavelengths around 1550 nm.

This disclosure provides systems, devices, and methods for practical,efficient beam steering that incorporate SLMs and that have significantadvantages over all previously mentioned methods. Such advantages caninclude:

-   -   1. having no moving parts    -   2. improving system performance by allowing previously        unavailable tradeoffs    -   3. enabling system cost reductions    -   4. scanning faster    -   5. having smaller size, weight, and power (SWaP)

The provided systems, devices, and methods can be used with a variety oflight sources. Non-limiting examples can include semiconductor lasers,solid-state lasers, fiber lasers, dye lasers, integrated photonicslasers, light-emitting diodes, thermal sources, or others, including anycombination thereof. Non-limiting examples of the source operation modecan include pulsed, continuous wave, frequency-modulated, or others,including any combination thereof. Non-limiting examples of pulsedoperation can use gain-switching, Q-switching, mode-locking,external-cavity modulation. In one example, the source can incorporatestabilization in order to narrow the laser linewidth, preventmode-hopping, increase the coherence length, improve the transverse beamquality, or others, including any combination thereof. Non-limitingexamples of stabilization can include optical filtering, temperaturestability, optical feedback, or others, including any combinationthereof.

Such devices can be used in reflection or transmission.

Solid-state SLMs (SS-SLMs) can be made using silicon (Si), silicondioxide (SiO₂), silicon nitride (Si₃N₄), silicon oxynitride(SiO_(x)N_(y)), silicon-germanium (SiGe), germanium (Ge), galliumarsenide (GaAs), aluminum arsenide (AlAs), aluminum gallium arsenide(AlxGa_(y)As), indium gallium arsenide (In_(x)Ga_(y)As), indiumphosphide (InP), aluminum gallium indium nitride (AlGaInN), aluminumgallium indium phosphide (AlGaInP), gallium nitride (GaN), mercurycadmium telluride (HgCdTe), other III-V materials or the like, orcombinations thereof.

A number of modulation techniques can be used to create the modulatingregion in SS-SLM pixels. In one example, quantum confining structuresare used. In such structures, the quantum-confined Stark effect (QCSE)can be used to modulate the amplitude and phase response. This effectemerges when carriers (e.g. electrons, holes, excitons) are confined inthe modulating region such that quantum effects are significant andchange the band structure as a function of applied voltage, therebychanging the absorption and phase response of the modulating region. Themodulating regions can contain one or more quantum confining structures,which may include one or more quantum wells, quantum wires, quantumdots, or combinations thereof, and can be arranged with uniform ornon-uniform spacing, and can be periodically or aperiodicially placed.The quantum structures can be positioned such that at least twostructures are in electronic communication (i.e. coupled), and/or suchthat at least one structure is not in electronic communication withother structures. For example, quantum structures in electroniccommunication can enable control of the overlap of electron and/or holewavefunctions, thereby allowing better control of the modulation effectsand which may include larger magnitude modulation effects. In anotherexample, the modulating region can contain one or more superlatticestructures. As an example, such structures can be created by varyingdoping type, doping concentration, material type, or combinationsthereof. The absorption and phase spectra can be modulated, for example,through the Wannier-Stark effect by applying a voltage. As well,modulation can be accomplished in semiconductors by applying an electricfield across the device, changing the carrier density through carrierinjection, depletion and/or excitation (e.g. optically, electrically),inducing thermo-optic effects applied to the modulating region, orcombinations thereof. Two or more modulation techniques can also be usedsimultaneously. Non-limiting examples can include a combination ofcarrier depletion and QCSE, or a combination of thermo-optic andsuperlattice biasing.

The actuation of SLM modulation can be done with a voltage, a current,or by exposure to electromagnetic radiation such as light. Whenmodulating using voltage, the voltage magnitude can have a lower limitof a voltage capable of generating a detectable modulation in a signal,and otherwise can, in some examples, be less than or equal to 1.8 V,less than or equal to 3.3 V, less than or equal to 5 V, less than orequal to 10 V, less than or equal to 20 V, or less than or equal to 100V. When modulating using a current, the current magnitude can have alower limit of a current capable of generating a detectable modulationin a signal, and otherwise be less than or equal to 1 mA, less than orequal to 10 mA, less than or equal to 100 mA, less than or equal to 1 A,or less than or equal to 5 A or more.

In some cases, the single-pass amplitude and phase response of the SLMpixels can be small compared to what an application requires. In thatcase, resonance effects can be used to achieve a stronger effect. Thiscan be accomplished by placing the modulating region in a resonator,which can be a symmetric Fabry-Perot resonator, an asymmetricFabry-Perot resonator, a Gire-Tournois resonator, or any other suitableresonant structure capable of accepting a modulating region.

Reflecting regions, which can be partially reflecting withreflectivities less than or equal to 95%, or fully reflecting withreflectivities greater than 95%, can be positioned to reflect light andare referred to herein as a resonator structure. A reflecting region caninclude a variety of materials and material combinations. For example, areflecting region can include, without limitation, metals, transparentconducting films (TCFs), conductive polymers, interference stacks, andthe like, including combinations thereof. Non-limiting examples of metalreflecting region materials can include aluminium, copper, gold, silver,and the like, including metal alloys and combinations thereof.Non-limiting examples of TCFs can include transparent conductive oxides(TCOs) such as metal oxides doped with indium (e.g. indium tin oxide),fluorine, aluminum, and the like, including dopant combinations thereof.Non-limiting examples of metal oxides can include oxides of tin,cadmium, zinc, or combinations thereof. Non-limiting examples ofconductive polymers can include polyacetylene, polyaniline, polypyrrole,polythiophene derivatives, or combinations thereof. The reflectingregions can also include interference stacks, which can be composed oflayers that are about a quarter-wave in thickness, and can be made ofsilicon (Si), silicon dioxide (SiO₂), silicon nitride (Si₃N₄), siliconoxynitride (SiO_(x)N_(y)), silicon-germanium (SiGe), germanium (Ge),gallium arsenide (GaAs), aluminum arsenide (AlAs), aluminum galliumarsenide (AlxGa_(y)As), indium gallium arsenide (In_(x)Ga_(y)As), indiumphosphide (InP), aluminum gallium indium nitride (AlGaInN), aluminumgallium indium phosphide (AlGaInP), gallium nitride (GaN), mercurycadmium telluride (HgCdTe), other III-V materials or the like, orcombinations thereof.

To adjust the achievable range of beam angles emerging from an SLM, forexample an SS-SLM, in one example structures can be placed on theexiting face of the device. Such structures could include scatterers,grating structures, other diffractive optic structures, or microlensarrays. In the last case, the microlens array can have a pitch that issubstantially equal to a integer multiple of the SLM pixel pitch,including a pitch that is equal to the SLM pixel pitch. The microlensarray can be bonded to or fabricated on the SLM, and can have numericalapertures as large as 0.87, as large at 0.72, as large as 0.66, or aslarge as 0.29.

Achieving large angular scanning range and high angular resolutionallows for larger, higher resolution imaging. The latter is enabled bykeeping the beam divergence angle smaller than the angular resolution. Ametric for these performance parameters can be the ratio of the SLMpixel-containing region area to individual SLM pixel area. In someexamples, this ratio can be greater than 25,000,000, greater than10,000,000, greater than 4,000,000, or greater than 2,000,000. In someexamples, the angular scanning ranges can be greater than about −4° toabout +4° with beam widths at 200 m away of less than about 15 mm orless than about 11 mm. In other examples, the angular scanning range canbe about −12° to about +12° with beam widths at 200 m away of less thanabout 15 mm or less than about 11 mm.

In another example, to application of voltages to actuate modulation,contacts can be used. A contact can be one continuous planesubstantially covering the SLM pixel-containing region of the device, ormay be patterned. One contact can be patterned such that the opticalfill factor is greater than 50%, greater than 70%, or greater than 90%.As part of the patterning, one or more etch processes can be used. Acontact can be placed between the modulating region and the substrate,or between the modulating region and the device outer surface. A contactcan incorporate, without limitation, metals, doped semiconductors,transparent conducting films (TCFs), conductive polymers, and the like,including combinations thereof. Non-limiting examples of metal contactregion materials can include aluminium, copper, gold, silver, andothers, including metal alloys and combinations thereof. Non-limitingexamples of semi-conductors can include n-doped semiconductors, and/orp-doped semiconductors, where said semiconductors can include silicon(Si), silicon dioxide (SiO₂), silicon nitride (Si₃N₄), siliconoxynitride (SiO_(x)N_(y)), silicon-germanium (SiGe), germanium (Ge),gallium arsenide (GaAs), aluminum arsenide (AlAs), aluminum galliumarsenide (AlxGa_(y)As), indium gallium arsenide (In_(x)Ga_(y)As), indiumphosphide (InP), aluminum gallium indium nitride (AlGaInN), aluminumgallium indium phosphide (AlGaInP), gallium nitride (GaN), mercurycadmium telluride (HgCdTe), other III-V materials or the like, orcombinations thereof. Non-limiting examples of TCFs can includetransparent conductive oxides (TCOs) such as metal oxides doped withindium (e.g. indium tin oxide), fluorine, aluminum, and the like,including dopant combinations thereof. Non-limiting examples of metaloxides can include oxides of tin, cadmium, zinc, or combinationsthereof. Non-limiting examples of conductive polymers can includepolyacetylene, polyaniline, polypyrrole, polythiophene derivatives, orcombinations thereof.

SS-SLMs can switch their modulation values faster than other types ofSLMs. For example, the single-pixel switching speed of an SS-SLM can beshorter than 100 ns, shorter than 500 ns, shorter than 1 μs, shorterthan 10 μs, or shorter than 100 μs. As well, the switching speed of theentire SS-SLM array can be faster than 10 kHz, 50 kHz, 100 kHz, 500 kHz,or even faster than 1 MHz.

The performance of a SLM can be improved by combining it with one ormore refractive and/or diffractive optical elements (DOEs). DOEs can bebinary using two or more discrete levels, provide apiecewise-continuously varying surface, be holographic, replicated,ruled, or other. One or more of the DOEs may also be directly fabricatedon the SLM device. For example, this can be accomplished on an SS-SLMthrough masking and etching the surface. Such elements can be used toshape the beam prior to steering it with the SLM, and can, for example,reduce the average SLM power requirements and/or simplify the SLMcontrol signals. In one example, one or more lenses are placed beforethe SLM to reduce the average voltages imposed on and power consumed bythe SLM.

As well, refractive optics or DOEs can be used to increasefunctionality. In one example, the optical elements lead to thegeneration two or more simultaneous beams. This can be advantageouswhen, for example, scanning coverage over an angular FOV is required.For example, with two beams, the angular range needed to scan across theFOV can be reduced by about a factor of two. For another example, withthree beams, it can be reduced by about a factor of three. In this way,the coverage of the FOV, the angular tuning range requirements, and thepower per beam can be traded off to improve system performance for givenapplication. For example, in a LIDAR application, a laser source canproduce sufficient optical power such that 2-10 beams can be supportedwith sufficient signal-to-noise ratio (SNR) for the application. In someconfigurations, multiple or even all beams can be emitted along a commonplane. In other configurations, one or more groups of two or more beamscan be emitted along one or more common planes.

An example is shown in FIG. 4. Shown are configurations with one outputbeam 409 steered to zero deflection angle 401, one output beam 410steered to full deflection 402, multiple output beams 411 steered tozero deflection angle 403, and multiple output beams 412 steered to fulldeflection angle 404. In all configurations 401-404, an input beam 405is incident on the beam steering device 406, and the maximum beam angle408 and associated beam path 407 at the edge of the field of view isshown, and is the same in all configurations 401-404. In configuration401 a single beam with no deflection is shown. To cover the FOV, thatsingle beam can be deflected by an amount approaching the maximum beamangle required by the FOV 408, resulting in a single, fully deflectedbeam 410 shown in configuration 402. Alternatively, configuration 403shows a device 406 configured to output multiple beams, whereconfiguration 403 shows multiple beams 411 with zero deflection angle.To cover the entire FOV, the fully deflected multiple beams 412 can bedeflected by a substantially smaller angle than the maximum beam angle408 required by the application's FOV. In this way, the beam steeringangular range can be reduced while still satisfying the FOV requirement.

In cases where the optical response to the steered beam light is alsoreceived and detected, for example as with a LIDAR application, andthere are multiple beams being simultaneously emitted, a system can beconfigured to detect received light, including determining from whichbeam the light returned. Such a system can incorporate a number ofdetectors equal to between one and the number of beams emitted, althoughmore detectors can be used to improve performance. This allows tradeoffsto keep the number of detectors low, and thereby allows tradeoffs insystem design between performance and cost. An example is shown in FIG.5. Configuration 501 shows where beams 506 b-506 d can be received inany combination, transmitted back through the beam steering device 505which then directs the received energy into multiple beams 507 a-507 e,each beam of which is detected by detectors 508 a-508 e, respectively.

For example, consider a beam steering system, which can be incorporatedinto a LIDAR system, having a SLM designed to emit three beamssimultaneously. Reflections of any two such beams will in general notlikely arrive at the device simultaneously. In the instance that itdoes, the light will interfere and substantially all go back to thelaser source only. More commonly, light will arrive from only one beamat a given time. In that case, that light will go back through the SLMand DOE, and be split again into multiple beams. By placing detectorsproperly, the split received beam can be detected and its originsdeduced by the relative signal from each detector. As well, eachdetector can individually measure the arrival time, and such multiplemeasurements can be used to improve the arrival time measurementaccuracy and/or precision, for example, by averaging multiplemeasurements. Furthermore, in some cases, this can be determined bylooking at the relative detector signal powers, thereby removing theneed to know the absolute power in the beams initially.

FIG. 5 provides more examples. All configurations 501-504 show a beamsteering device 505. Configuration 501 shows all possible beam paths,including a first through third received beam 506 a-c, a first throughfifth beam 507 a-507 e, and a first through fifth detector 508 a-508 e.In configuration 502 showing the center beam path received, power isonly being received in the form of the second received beam 506 c. Asshown, the beam steering device distributes beam 506 c's power intofirst through fifth beams 507 a-507 e, which are then detected by firstthrough fifth detectors 508 a-508 e, respectively. This provides a)between one and five signals of relative magnitudes, and b) between oneand five timing measurements. In this way, uncorrelated noise (e.g.noise from the measurement system) can be averaged, and the fact thatthe power came from beam 506 c can be determined.

In configuration 503 showing a non-center beam path received, power isonly being received in the form of the first received beam 506 b. Asshown, the beam steering device distributes beam 506 b's power intobeams 507 a-507 e, which are then detected by detectors 508 a-508 e,respectively. This provides a) between one and five signals of relativemagnitudes, and b) between one and five timing measurements. Similar toconfiguration 502, uncorrelated noise (e.g. from the measurement system)can be averaged, and the fact that the power came from beam 506 b can bedetermined.

In configuration 504 showing a center and non-center beam path receivedsimultaneously, power is received simultaneously from first beam 506 band second beam 506 c. Here, simultaneously means that the difference inthe time of flight of beams 506 b and 506 c is less than the beam pulseduration. As shown, the beam steering device distributes beam 506 b'sand beam 506 c's power into beams 507 a-507 e, which are then detectedby detectors 508 a-508 e, respectively. This provides a) between one andfive signals of relative magnitudes, and b) between one and five timingmeasurements. Similar to configuration 502, uncorrelated noise (e.g.from the measurement system) can be averaged, and the fact that thepower came from both beam 506 b and 506 c can be determined. If thedifference in time of flight between beams 506 b and 506 c exceeds thecoherence time, then the signals will add in power. As well, if thedifference in the time of flight between beams 506 b and 506 c isshorter than the coherent time, then the signals will interfere, and thesignals detected by detectors 508 a-508 e will show this in the form of,for example, an interference pattern. In some cases, if the coherencetime is shorter than the pulse durations, the presence of interferencein the signal could be used to more accurately deduce various parametersof interest, for example, the arrival times and/or the relative velocityof the two targets associated with the returned beams.

The sensors used to detect the return signals can incorporate electronicamplification or gain. In some examples, the amplification or gain canbe achieved through an avalanche process, for example by using anavalanche photodiode, or a photomultication process using, for example,a photomultiplier tube. In other examples, the amplification or gain canbe achieved through a photoconductive process. In yet other examples,the amplification or gain can be achieved through the supportingdetection circuit and can involve one or more transistors. In someexamples, the sensor elements that have amplification or gain can beoperated in Geiger mode. In other examples, the sensor elements thathave amplification or gain can be operated in a substantially linearmode.

The sensors can be made using a variety of materials. Non-limitingexamples can include silicon (Si), silicon dioxide (SiO₂), siliconnitride (Si₃N₄), silicon oxynitride (SiO_(x)N_(y)), silicon-germanium(SiGe), germanium (Ge), gallium arsenide (GaAs), aluminum arsenide(AlAs), aluminum gallium arsenide (AlxGa_(y)As), indium gallium arsenide(In_(x)Ga_(y)As), indium phosphide (InP), aluminum gallium indiumnitride (AlGaInN), aluminum gallium indium phosphide (AlGaInP), galliumnitride (GaN), mercury cadmium telluride (HgCdTe), other III-V materialsor the like, or combinations thereof. In still other additionalnon-limiting examples, the sensor may contain at least one of Al, As,Ga, Ge, In, N, O, P, or Si. The material can be at least partiallytextured. The texturing can be done with a chemical, mechanical, orlaser process, for example using a black silicon process, where thetextured region is at least partially within the photocarrier generationregion and where the textured region leads to enhanced photoresponse.

In some examples, the sensor can be fabricated with a CMOS process. Inother examples, the sensor can be a charge-coupled device (CCD).

The sensor can be operated in an incoherent detection mode. It can alsooperate in a coherent detection mode, for example by interfering aportion of the source electromagnetic radiation with returnedelectromagnetic radiation. In the latter case, the sensor can be used todetect velocity, for example, with a single measurement. Velocity canalso be determined by making multiple measurements over time andcalculating velocities from that. Velocity can also be determined fromDoppler shifts when operating in a coherent detection regime.

Additionally, data processing performed after acquisition can be done bya processor, which can be a single processors or multiple processors,including single core processors and multi-core processors. Non-limitingexamples of processors can include central processing units (CPUs),graphics processing units (GPUs), application-specific integratedcircuits (ASICs), digital signal processors (DSPs), field-programmablegate arrays (FPGAs), application-specific instruction set processors(ASIPs), and the like, including various combinations thereof. In someexamples, the processor can be a custom processor designed for the dataprocessing task. Artificial intelligence techniques can also be appliedto the data.

One example subsystem includes a SLM and a DOE, where the SLM and DOEcan, in some examples, be monolithically fabricated, and in otherexamples, can be intimately attached to form a single device. In someexamples, the DOE can have lateral characteristic length that areapproximately equal to or greater than the wavelength of the light used,for example 1550 nm or 2000 nm, and in other examples the lateralcharacteristic length scales can be substantially less than thewavelength of light. In other examples, the DOE can be a 1-D or 2-Dgrating. In some cases, the DOE can be aligned to the SLM withtolerances larger than the SLM element pitch, for example 1.7 μm, 2.8μm, 5.6 μm or 11.2 μm, and in other cases it can be aligned withtolerances smaller than the SLM element pitch. In some cases, the DOE iscloser to the SLM, and is not in the far-field. In some cases, thedistance from the SLM to DOE can be about 10 μm, 100 μm, 1 mm, 10 mm, or100 mm. In some examples, the DOE can be on the input face of the SLM,and serve in some examples to shape the output beam and/or split theinput beam into multiple beams. In other examples, the DOE can be on theexit face of the SLM, and serve to, in addition to other functions,increase the numerical aperture of the light coming from some or all ofthe SLM elements to values such as 0.87, 0.72, 0.66, or 0.29, which inturn can increase the power efficiency over a wider angular FOV.

Another example subsystem includes a SLM and a microlens array, wherethe SLM and microlens array, in some examples, can be monolithicallyfabricated, and in other examples, can be intimately attached to form asingle device. The microlenses can be aligned with the SLM pixels, suchthat a microlens covers an integer number of SLM pixels. For example,each microlens could cover between 1 and 25 SLM pixels, or could cover1-100 SLM pixels. These microlenses can have a high numerical aperture,such as 0.87, 0.72, 0.66, or 0.29, to allow for a wide angular FOV inwhich diffraction efficiency is high.

Example 1 Wavelength 1550 nm Coherence Coherent SLM Si, PM Add'l ShapingMonolithic DOE Spots Multiple Distribution of Light MonolithicMicrolenses Detection InGaAs APDs

In one example system, a Si-based SS-SLM comprised of vertical waveguidestructures can be used that can impose substantial PM. A verticalwaveguide structures can be monolithically fabricated on the SS-SLMchip, for example on the input face, in order to provide multiplediffracted beams up, for example, up to third order (i.e. 7 beams)horizontally and up to first order (i.e. 3 beams) vertically, for atotal of 21 beams. The SS-SLM can be 8 mm×8 mm in size, and can havewaveguides such that the pitch is about 1.0 μm×1.0 μm. Microlenses canalso be fabricated, for example monolithically on the output face of thechip, in order to control the diffraction efficiency. The system can beconfigured for 1550 nm operation and coherent detection, where a portionof the source light is retained and interfered with received light onthe sensor. The system can use the same optical path for receiving inaddition to transmitting. InGaAs APD point detectors can be used todetect the multiple received beams.

Example 2 Wavelength 2000 nm Coherence Incoherent SLM Si, PM + AM Add'lShaping None Spots Single Distribution of Light None Detection Ge APDLinear Array

In another example system, a Si-based SS-SLM can be used that hassubstantially constant PM and some AM. The system can be designed for2000 nm operation. The system can be operating for incoherent detection,where a portion of the source light is retained and interfered withreceived light on a, for example, Ge APD linear array. Light can bereceived using the same optical path used for transmitting.

In another example, shown in FIG. 6, a system is shown from theviewpoint of the +y axis 601, the +x axis 602, and the +z axis 603. Thissystem can include a SLM 607 and one or more static DOEs 606 disposed onit. The SLM 607 may be in communication with a controlling device 609,which can be a chip, and which can be made using a CMOS process. One ormore light sources 604, which can be laser sources, emits one or morebeams 605 that is then incident from an angle of incidence that isgreater than normal incidence on the DOE 606 surface. Because the beamsfrom lasers 604 can be elliptical, the incident angle can be selected sothat the projection of the beam onto the chip surface is substantiallycircular, thereby reducing the need for or complexity of additional beamshaping optics. The light 605 can then pass through the static DOE 606,interact with the SLM 608, reflect back through the DOE 606, and thenexit the system. The two passes through the static DOE 606 in total canshape the divergence, beam waist location, and other characteristics ofthe first through third exit beams 608 a-608 c. The interaction with theSLM 608 can determine the efficiency, count, and direction ofpropagation of diffracted beams 608 a-608 c in both directions lateralto the chip normal. In this way, the system can create multiple beams608 a-608 c, and direct them dynamically to enable non-mechanical, highspeed scanning. When some of the light exiting the device 608 a-608 c isreflected back into the device, the light can substantially retrace thesame paths that through the system, and then can be detected by a one ormore photodetectors 610, which could be one or more point detectors, alinear array, or a 2-D array, and can incorporate signal gain.

In another example, shown in FIG. 7, a system is shown from theviewpoint of the +y axis 701, the +x axis 702, and the +z axis 703. Thissystem can include a SLM 707 and one or more static DOEs 706 disposed onit. The SLM 707 may be in communication with a controlling device 709,which can be a chip, and which can be made using a CMOS process. One ormore light sources 704, which may be laser sources, emit one or morebeams 705. Because the beams from light source 704 can be elliptical,optics may be incorporated to reshape the beams to be substantiallycircular. The beam 705 is reflected by a beam splitter 711, which can bea polarization beam splitter, and is reflected downward as shown. Thelight then interacts with one or more polarization optics 712 which can,for example, convert the light polarization from linear to circular. Thelight 705 can then pass through the static DOE 706, interact with theSLM 707, reflect back through the DOE 706, pass through the one or morepolarization optics 712, which can for example convert the polarizationfrom circular to linear polarization, and then exit the system. The twopasses through the static DOE 706 in total can shape the divergence,beam waist location, and other characteristics of the first throughthird exit beams 708 a-708 c. The interaction with the SLM 708 candetermine the efficiency, count, and direction of propagation ofdiffracted beams 708 a-708 c in both directions lateral to the chipnormal. In this way, the system can create multiple beams 708 a-708 c,and direct them dynamically to enable non-mechanical, high speedscanning. When some of the light exiting the device 708 a-708 c isreflected back into the device, the light can substantially retrace thethe same paths that through the system, and then can be detected by oneor more photodetectors 710, which could be one or more point detectors,a linear array, or a 2-D array, and can incorporate signal gain.

Below are disclosed additional systems, devices, and methods forpractical, efficient beam steering that have significant advantages overother methods.

One architecture that can be used to make an optical phased array beamsteering chip incorporates an array of vertical waveguides. Within eachwaveguide, two or more resonators may be created. In some examples, theresonators are designed so that actuating the phase response does notcause substantial changes in the amplitude response. The resonators canhave similar or different resonances when not coupled, or they can havedifferent resonances when not coupled.

The height of the vertical waveguides can be between 3 um and 50 um,between 5 um and 25 um, or between 10 um and 20 um. The waveguide widthscan be about 5 um, about 2 um, about 1 um, about 0.5 um. The waveguidecross-sectional shape can be rectangular, square, round, elliptical, orany other closed shape, and that shape can contain region of one or moretypes of material. The waveguides can be arranged near each other, witha gap between them, the size of which can be around 2 um, around 1 um,around 0.5 um, around 0.3 um, or around 0.2 um. The gap can be filledwith material with a lower refractive index than the waveguide, to allowfor waveguiding. The gap can be filled with material that iselectrically insulating in order to electrically isolate the waveguidesfrom each other.

In some examples, the waveguides can contain one or more quantum wells.In other examples, the waveguides contain one or more doped layers. Insome examples the waveguides can be substantially made of III-Vsemiconductors. In some examples the III-V can be AlAs and GaAs. Inother examples the waveguides can be made of silicon.

In one example, the vertical waveguide array is shown in FIG. 9 from aside view. The pixels are formed on an undoped semiconductor substrate901. A doped ground plane 906 is provided. In this example, each pixelconsists of two types of regions. One type is a region 902 a-c whosephase response can be modulated. The other is a region 903 a-d that is apartially reflective structure. As such, three resonators are formed.One resonator is formed by reflectors 903 a-b and region 902 a. Anotherresonator is formed by reflectors 903 b-c and region 902 b. Yet anotherresonator is formed by reflectors 903 c-d and 902 c. These resonatorsare designed to enable phase modulation up to frit in magnitude, whilekeeping the amplitude response substantially flat. Between thewaveguides are regions 907 of refractive index that is lower than therefractive index in at least one of regions 902 a-c. Region 907 can bevacuum, air, an oxide, a semiconductor, or other suitable material.

On top of the waveguide a semiconductor region 908 can be formed inwhich circuitry can be fabricated for controlling the pixel's operation.In some examples, the control circuitry can contain one or moretransistors. In some examples, the waveguide array can have region 909disposed on it to, for example, allow for metal signal lines, vias, andelectrically insulating material so that pixels can be electricallyactuated and controlled.

In some examples, the regions that can be phase modulated 902 a-c do sothrough changes in carrier concentration. This can be through any means,including but limited to carrier injection, or carrier depletion.

In one example, the regions 902 a-c that may be phase modulated consistof alternating layers of p-doped and n-doped semiconductor. Betweenthose layers there can optionally be one or more layers, one or more ofwhich will have substantially different doping than the doping of boththe alternating p-doped and n-doped layers. In some examples, theperiodicity of the n- and p-doped layers will be about 100 nm, or about50 nm, or about 30 nm.

In some examples, a region 904 of the waveguide sidewall can be p-dopedsuch that that region 104 makes electrical contact with the p-dopedlayers in the regions 902 a-c, and a region 905 of the waveguidesidewall can be n-doped such that that region 905 makes electricalcontact with the n-doped layers in the regions 902 a-c. In someexamples, a voltage potential can be put across the two doped regions904 and 905 so as to cause a change in carrier density at each n-dopedand p-doped interface. In this way, the carrier density in the volume ofthe waveguide can be modulated, and thereby the phase modulated. Thedoping densities can be between 10¹⁸ cm⁻³ and 10²² cm⁻³, or between 10¹⁸cm⁻³ and 10²⁰ cm⁻³, or between 5×10¹⁸ cm⁻³ and 5×10¹⁹ cm⁻³. Note thatthe doping polarity can be switched in some examples.

One advantage the previous example offers is that fringing fields canhave little impact on a neighboring waveguide, thereby mitigating thiscommon problem with optical phase arrays that can lead to poorperformance.

In another example, the waveguide may be substantially round orelliptical in cross-section, where there can be one or more regionssubstantially in the middle of the waveguide that are doped with onepolarity, and where a bounding region of the waveguide is doped with theopposing polarity. In this case, the bounding polarity can be kept atconstant electrostatic potential, and the center region(s) voltageschanged to actuate the phase. This architecture can then isolate a givenwaveguide from the electrical signals of any nearby waveguide.

In some examples, the semiconductor in any of the previous examples canbe silicon. The doping used can be phosphorus, arsenic, boron, or anyother suitable doping material. In some examples, the gaps between thewaveguides can be filled partially or fully with silicon dioxide,silicon oxynitride, or silicon nitride. The gaps may also be filled withmetal, such as aluminum, copper, tungsten, titanium, or any suitablemetal.

The waveguide circuitry is used to control the waveguide. One example ofa waveguide circuit without reset 1001 is shown in FIG. 10, where thewaveguide structure that is to be biased 1002 is represented by a diodesymbol. Waveguide circuit 1001 shows a two-transistor circuit, wherethree signal comes to the waveguide: a) a row selecting signal 1004 tocontrol a row-selecting transistor 1003 a, b) a column selecting signal1005 to control a column-selecting transistor 1003 b, and c) the biasvoltage conductor 1006 to impose on the waveguide 1002. Another examplecircuit with reset 1000 is the same as example circuit 1001, with anadditional transistor 1003 c, controlled by the reset signal 1007, whichcan impose the bias voltage from conductor 1008 on the waveguide 1002 toreset the bias.

In some examples, the waveguide array could be 100 million elements ormore. In general, setting different biases on each pixel in series canin some instances require signal pathways that can send data at 10's,100's or even many 1000's of GB/s. In many instances, the fact that beamsteering is being done can result in a periodicity across the array inthe signal pattern required, the periodic pattern of which will bereferred to as a unit cell. In examples where the steering angle issteep, that repeating unit cell can be reasonably small. In this examplethen, the repeated pattern allows multiple waveguide biases to beupdated in parallel, reducing the data rate required by approximatelythe number of unit cells over the entire array. In another example,where the steering angle is shallow, the unit cell is large. However inthis case, waveguides can be grouped in regions where they havesubstantially the same bias and biased to the same value. This way,again, multiple pixels can be updated in parallel, thereby reducing thedata rate required by approximately the number of waveguides within agroup with common bias.

In one example, m bias levels are used for each linear dimension. Inthis case, the number of updates required can be limited to m². Forexample, if m=8, at most 64 clock updates will be required. If each biasimposition requires one clock tick, then a clock of 64 MHz can besufficient to update an array of any practical size.

The beam steering chips herein described can be used such that lightincident and exiting the chip do so through the substrate 1100 beforeand after, respectively, interacting with the beam steering opticalphased array layer 1101, as shown in FIG. 11. In some examples, thesubstrate is of higher refractive index that the surroundingenvironment. In this case, a beam steerer that would have a smallangular range can have the angular range increased by refraction at thesubstrate backside. Beams that exit at nearly normal incident angles1102 will exit at nearly normal angles. Beams that exit at small angles1103 will have the angle of exit increased moderately upon refraction.Beams that exit at larger angles 1104 will have their exit angleincrease significantly more than shallower angle beams 1103.

In one example, 1550 nm light is steered by a silicon beam steering chipdisposed on a silicon substrate. In this example, light exiting the beamsteering layer, but is still in the silicon substrate, can have a rangeof achievable angles might be ±10°. Upon exiting the substrate, theangular range will be increased to about ±36°. In another example, therange of achievable angles might be ±15° which, upon exit from thesubstrate, can be increased to a range of achievable angles of ±62°.

Another benefit of using the circuit such that light travels through thesubstrate is that the beam steering layer is closer to the backsidewhere thermal management can be more effectively done.

In some instances, it can be desirable to use a single beam steeringchip to steer multiple beams simultaneously. One example of a way toachieve multi-laser beam steering 1200 is shown in FIG. 12. A source ofmultiple beams 1201 emit beams that pass through optionally one or moreoptics 1202. The resulting bundle of beams 1203 then is incident on thebeam steering chip 1204, which steers all beams simultaneously, whichthen exit as a newly directed bundle of beams 1205. In this example, thesource of multiple beams can be an array of laser diodes, an array ofvertical cavity surface emitting lasers (VCSELs), a bundle of opticalfibers, or others. The beams within the array can be mutually coherent,incoherent, partial coherent, or any combination thereof. The optionaloptics can be chosen so that the bundle of beams 1203 are converging,but where each individually is diverging to substantially fill the beamsteering chip 1204's aperture.

Below are disclosed additional systems, devices, and methods forpractical, efficient beam steering that have significant advantages overother methods.

In some examples of optical phased arrays incorporating verticalwaveguides, one or more tapers can be formed at the end of one or morewaveguides into which light can be coupled. This can increase the lightcoupling efficiency. The sidewall angle from vertical of the tapers canbetween 0° and 5°, between 0° and 10°, between 0° and 15°, or between 0°and 30°, and can be constant along the length of the at least one taper,or the angle can vary with position. An example showing at least onetaper connecting to at least one vertical waveguides is shown in FIG.13.

In some examples of optical phased arrays incorporating verticalwaveguides, two or more nearest-neighbor waveguides can be sufficientlyclose to each other that an appreciable amount of optical power cancross-coupling from one waveguide to another. For example, anappreciable amount of optical power can mean more than 20%, more than10%, more than 5% or more than 1%. Cross-coupling can be suppressed bymaking the mode propagation constants of nearest-neighbor waveguidesdissimilar. This can be accomplished by varying the cross-sectionalshape, size, and/or orientation of the two or more waveguides. Someexamples 1400-1402 are shown in the top view in FIG. 14. Example 1400shows at least two nearest-neighbor waveguides that are the same shapeand size, but are rotated 90° to one another. Example 1401 show at leasttwo nearest-neighbor waveguides that are the same shape but differentsize. Finally, example 1402 shows at two or more nearest-neighborwaveguides that are of different shapes but the same size. Any suitablevariation or combination of variations in nearest neighbor waveguidesthat changes their propagation constant can work in the manner describedherein.

In some examples of optical phased arrays incorporating verticalwaveguides, at least one vertical waveguide can include one or moreregions with a refractive index lower than the surrounding waveguide andthat overlaps substantially with the optical mode. Each of the at leastone lower refractive index regions can have one or more small dimensionsin comparison to the wavelength of light. The at least one or more lowrefractive index region can be comprised of a material with anelectrically actuatable refractive index, such that the propagationconstant of the entire mode can be substantially actuated. The materialin the at least one low refractive index region can also be of highelectrical resistance, such that application of a bias across the atleast one low refractive index region leads to very little current flowand power consumption. The high refractive index material on either sideof the at least one low refractive index region can be used aselectrodes for applying an electrical bias across the at least one lowrefractive index region.

One example of at least one low refractive index region included in atleast one vertical waveguide of an optical phased array incorporatingvertical waveguides is shown in FIG. 13 from the side view 1300. Anintrinsic silicon substrate 1301 is used, on which a silicon taper 1302is optionally disposed in order to enable efficient coupling into thewaveguides 1309 of optical power entering the device from the substrate1301. A p-doped silicon contact 1303, an optically reflective region1304, a control region 1305, and a low refractive index region 1307comprises a waveguide 1309. The waveguide can be disposed upon a taper1302, or if a taper 1302 is not included, it can be disposed directly onthe substrate 1301. Each waveguide 1309 is optically separated by region1308, in which a refractive index lower than the effective refractiveindex of the waveguide 1309 is provided. A region 1306 containing signallines, vias, etc. is then disposed on top of the waveguide array. Region1305 can provide transistors, doped contact regions, etc. to allowcontrol of the bias imposed on each waveguide 1309. Region 1307 can beencapsulated by, for example, layer 1306, can be open to the ambientenvironment through openings in layer 1306 (not shown), or can be opento the ambient environment by other means (not shown). This region 1307contains a material whose refractive index can be effectively modulatedby a voltage provided across the region 1307 by region 1303.

In some examples, one of the dimensions of at least one low refractiveindex region will be less than 200 nm. In another example, one dimensionwill be less than 100 nm. In yet another example, one dimension will beless than 50 nm. In still another example, one dimension will be lessthan 25 nm.

The material comprising the low refractive index region can besemiconductor, a dielectric, a polymer, a liquid crystal, or anysuitable material, or any combination thereof. Semiconductors caninclude silicon, germanium, gallium arsenide, aluminum arsenide,aluminum gallium arsenide, indium phosphide, indium gallium arsenide,gallium nitride, strained variants thereof, and others. Dielectrics caninclude silicon dioxide, silicon nitride, silicon oxynitride, andothers. Polymers can be nonlinear, electro-optic, dendritic, can containhyperpolarizable chromophores, and can be poled. These polymers caninclude PMMA, polycarbonate, sol-gel, and others. Chromophores caninclude YLD 124, DR1, CLD1, AJL8, AJLS102, JT1, AJ307, AJ309, AJ404, andAJ-CKL1. Liquid crystals can be of the thermotropic, lyotropic, ormetallotropic phases. Thermotropic phases can include the nematic phase,smectic phase, or other phases of liquid crystal. Applicable liquidcrystals can be organic, and can incorporation lipids, proteins, DNA,polypeptides, and others. They can also be inorganic, and can includevarious oxides such as vanadium oxide, carbon nanotubes, graphene, andothers. Liquid crystals can include 4-Cyano-4′-pentylbiphenyl (5CB),various biphenyl (BP) molecules such as E7,N-(4-Methoxybenzylidene)-4-butylaniline (MBBA), and others.

In some examples of optical phased arrays incorporating verticalwaveguides, at least one waveguide can be designed to operate intransmission mode. In this example, the control lines and circuitelements can be at least partially placed away from the exit aperturesof each vertical waveguide, to reduce the optical loss. At least onetaper can be used on the inputs of the vertical waveguides intransmission mode, and optionally at the outputs of at least one of thevertical waveguides.

An example structure is shown in FIG. 15. This configuration 1500includes a substrate 1501, on which a taper 1502 can optionally beincluded for each waveguide 1507. Upon this is a region 1503 withinwhich the phase is actuated. A region 1504 is then in contact withregion 1503, and can be used to control the phase actuation. Regions1506 separate each waveguide 1507, and region 1505 is disposed on top ofthe waveguides to provide signal lines, vias, and other necessarycircuit structures. To reduce optical loss, the control structures inregion 1505 can be placed substantially over regions 1506, and theelements in region 1504 can be placed near the edges of the waveguide1507. The waveguides 1507 can be any suitable waveguide structure, andcan include narrow regions described previously and shown in FIG. 13.

In some examples of optical phased arrays, waveguides can be arranged toreceive light in a direction normal to a surface upon which they arealigned. For example, waveguides arranged in an array along a surfacereceive light from a direction that is normal to that surface. In a morespecific example, a waveguide or array of waveguides disposed on aplanar substrate receive light from a direction that is normal to theplane of the support substrate, which in many cases, would be light thatis transmitted through the support substrate and into the waveguides. Inother cases, however, such would include light being transmitted intothe waveguides and toward the support substrate. In yet another example,the light can be delivered through substrate or other material layer tothe waveguide at any oblique angle that can facilitate the intendedfunctionality of the device. In some examples, the oblique angle can bebetween 0° and 0.1°, between 0° and 1°, between 0° and 5°, between 0°and 10°, between 0° and 45°, or between 0° and 89°. In some examples,waveguides that receive light through the substrate upon which they aredisposed can be referred to as “vertical waveguides.” In other examples,a vertical waveguide can describe a waveguide where light passes throughhe waveguide and into the substrate upon which they are disposed.

In some cases the support or other substrate upon which an array ofwaveguides is disposed may not be aligned along a 2D plane; in suchcases, the direction of the light entering the waveguide can bedetermined from the plane established from the region upon which thewaveguide sits. It is understood that the determination ofdirectionality of transmitted light to a waveguide is well within theabilities of one of ordinary skill in the art.

What is claimed is:
 1. A waveguide device, comprising: a pair ofwaveguides disposed on a support substrate and structurally positionedto receive light transmitted through the support substrate, where eachwaveguide comprises; a reflective region positioned to reflect impinginglight toward the support substrate; a core region extending from thereflective region to the support substrate, the core region furthercomprising; a first contact region and a second contact regionelectrically isolated from one another disposed between the reflectiveregion and the support substrate; and a light concentrator disposedbetween the first contact region and the second contact region, whereinthe first contact region and the second contact region are operable tocreate a voltage drop across the light concentrator, and wherein thelight concentrator has a lower refractive index compared to therefractive indexes of the first contact region and the second contactregion; and a confinement structure surrounding the periphery of eachwaveguide, wherein the confinement structure has a lower refractiveindex compared to the refractive indexes of the first contact region andthe second contact region.
 2. The device of claim 1, wherein the supportsubstrate is a semiconductor substrate.
 3. The device of claim 2,wherein the support substrate is a silicon substrate.
 4. The device ofclaim 2, wherein the confinement structure extends into thesemiconductor substrate.
 5. The device of claim 4, wherein theconfinement structure includes a trap structure in the semiconductorsubstrate to improve light trapping.
 6. The device of claim 1, furthercomprising a control layer electrically coupled to the first contactregion and to the second contact region, wherein the control layerfurther comprises control lines to control the first contact region andthe second contact region.
 7. The device of claim 1, wherein the pair ofwaveguides are adjacent to one another.
 8. A vertical waveguide array,comprising: a plurality of vertical waveguides disposed on a supportsubstrate in an array, where each vertical waveguide further comprises;a reflective region positioned to reflect impinging light toward thesupport substrate; a core region extending from the reflective region tothe support substrate, the core region further comprising; a firstcontact region and a second contact region electrically isolated fromone another disposed between the reflective region and the supportsubstrate; and a light concentrator disposed between the first contactregion and the second contact region, wherein the first contact regionand the second contact region are operable to create a voltage dropacross the light concentrator, and wherein the light concentrator has alower refractive index compared to the refractive indexes of the firstcontact region and the second contact region; and a confinementstructure surrounding the periphery of each waveguide, wherein theconfinement structure has a lower refractive index compared to therefractive indexes of the first contact region and the second contactregion.
 9. The vertical waveguide array of claim 8, wherein theplurality of vertical waveguides is disposed on the support substrate ina one-dimensional (1D) array,
 10. The vertical waveguide array of claim8, wherein the plurality of vertical waveguides is disposed on thesupport substrate in a two-dimensional (2D) array,